Would love to make a small all-flash NAS, but the only one I know about does not have it: https://www.asustor.com/en/product?p_id=80
$650 QNAP TS435XeU 1U NAS supports 4GB-32GB ECC SODIMM, 4xSATA, 2xNVME, based on Marvell/Armada CN9130 Arm SoC. Debian for Arm64 can be installed via serial console.
Some 4x4 Ryzen Embedded V1000 mini PCs support ECC SODIMM, e.g. https://www.sapphiretech.com/en/commercial/fs-fp5#Specificat..., possibly ASRock.
You can go to 96 GB.
With displays: https://www.solid-run.com/industrial-computers/bedrock-r7000...
Would love to make a small all-flash NAS, but the only one I know about does not have it: https://www.asustor.com/en/product?p_id=80